Prep new post

2013/01/31/dynarray.cpp

@@ -0,0 +1,86 @@
+
+
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <iostream>
+#include <limits>
+#include <vector>
+
+using namespace std;
+
+class WallClockTimer {
+public:
+    struct timeval t1, t2;
+    WallClockTimer() :
+        t1(), t2() {
+        gettimeofday(&t1, 0);
+        t2 = t1;
+    }
+    void reset() {
+        gettimeofday(&t1, 0);
+        t2 = t1;
+    }
+    int elapsed() {
+        return ((t2.tv_sec - t1.tv_sec) * 1000) + ((t2.tv_usec - t1. tv_usec)
+                / 1000);
+    }
+    int split() {
+        gettimeofday(&t2, 0);
+        return elapsed();
+    }
+};
+
+
+int test(size_t N) {
+	vector<int> x;
+	for(size_t i = 0 ; i < N ; ++i ) {
+		x.push_back(i);
+	}
+	return x.back();
+}
+
+
+int testManual(size_t N, const int multiplier, const int div = 1, const int constant = 0) {
+	int * x = new int[1];
+	size_t s = 1;
+	for(size_t i = 0 ; i < N ; ++i ) {
+		if(i == s) {
+			int * nx = new int[ multiplier * s / div + constant ];
+			memcpy(nx,x,s*sizeof(int));
+			delete[] x;
+			x = nx;
+			s = multiplier * s / div + constant;
+		}
+		x[i] = i;
+	}
+	return x[N-1];
+}
+
+
+
+int overall(size_t N) {
+	int bogus = 0;
+	WallClockTimer t;
+	t.reset();
+    bogus += test(N);
+    int delay = t.split();
+    cout << "STL vector " << N /(delay * 1000.0) << endl;
+
+    for(size_t factor = 1; factor <= 6; ++ factor) {
+		t.reset();
+    	bogus += testManual(N,2+factor,2,factor&1==0 ? 0 : 1);
+    	delay = t.split();
+    	cout << "pointer-based "<< (factor +2)/2.0<< " : " << N /(delay * 1000.0) << endl;
+    }
+    return bogus;
+}
+
+int main() {
+	int bogus = overall(1024*1024);
+	bogus += overall(1024*1024);
+	bogus += overall(1024*1024*64);
+	bogus += overall(1024*1024*64);
+
+	return bogus;
+}

extra/integerlog.cpp

@@ -12,7 +12,8 @@ using namespace std;
 class WallClockTimer {
 public:
     struct timeval t1, t2;
-    WallClockTimer() :
+
+    () :
         t1(), t2() {
         gettimeofday(&t1, 0);
         t2 = t1;